One of the evil effects attendants upon the development of the technology and the industry is an environmental pollution. The kind and the reasons of the environmental pollution are much and complicated.
Air pollution, water pollution and noise pollution become the social problems seriously. Then the air pollution mainly depends upon the exhaust gas of the automobile and the exhaust gas causes the headache, the cough and the health trouble.
The exhaust gas is classified into three classes that the exhaust gas from the internal combustion engine, the blow-by gas from the crankcase of the engine and the evaporation gas evaporated in a fuel tank and a carburetor.
The exhaust gas from the combustion engine is a gas exhausted from the engine after igniting the mixed fuel with air. The component of the exhaust gas from the engine includes not only a water vapor, a nitrogen and a carbonic acid gas that inoffensive to the person but also CO, hydrocarbon, nitric oxide, carbon grains and a lead oxide etc that offensive to the person.
Many study have been progressed to remove the harmful material included in the exhaust gas from the combustion engine and discharge the purified gas that is not harmful to the person from long ago.
FIG. 2 shows an apparatus for treating the exhaust gas of an internal combustion engine that is a super ultra low environmental pollution (SULEV) engine made by the HONDA Company of Japan. The apparatus includes an exhaust manifold 30 made with stainless steel having a low thermal conductivity. A catalyst 32 is connected with the exhaust manifold 30, and a hybrid catalyst 61 and a electrically heated catalyst (EHC) 60 are serially connected to the catalyst 32
FIG. 1 shows an apparatus for treating the exhaust gas of an internal combustion engine that is a super ultra low environmental pollution (SULEV) engine made by the NISSAN Company of Japan. The apparatus includes an EHC 60 and a under floor TWC 62. The exhaust gas is discharged into the atmosphere through the EHC 60 and the under floor three-way catalyst or three-way catalytic converter (TWC) 62 in turn and purified. An HC-absorber 50 is connected to the rear end of the TWC 62 through the bypass line 51.
The after treatment device of the exhaust gas according to HONDA uses a catalyst having high density of 1200 cells per square inch having a low efficiency. Therefore, the after treatment device of the exhaust gas according to HONDA is of no practical use.
Furthermore, the after treatment device of the exhaust gas according to NISSAN needs two valves for controlling the large EHC 60 and the under floor TWC 62, and sometimes the valves are worked wrong. Therefore the exhaust gas is not properly purified.